Corn silage is a popular forage for ruminant animals because of its high energy and digestibility. Corn grain is often added to ration formulations to improve nutritional balance. Kernel hardness and texture play an important role in starch digestibility. A softer kernel or a hybrid that is harvested when it is less mature is easier to digest in the rumen. Naturally-occurring maize mutations, such as brown midrib (BMR), floury2 (fl2), and opaque2 (O2) have become a focus of silage product development because they are associated with a softer kernel. BMR germplasms, for example, have reduced cell wall lignin content. Cherney et al. (1991) Adv. Agron. 46:157-98. Plants with the fl2 or O2 mutations produce soft, starchy endosperm with irregularly shaped protein bodies and higher lysine content than wild type. Coleman et al. (1997) PNAS 94:7094-97. Adding grain with the fl2 or O2 mutations to rations may increase digestibility in ruminants, reducing the amount of grain needed for nutritional requirements and reducing the need for kernel processing at harvest. See Ladely et al. (1995) J. Anim. Sci. 73:228-235.
The floury2 trait is reportedly associated with a mutation in one of the members of the zein gene family, the major prolamin storage proteins in maize seed. Song et al. (2001) Gen. Res. 11:1817-25. Introgression of the fl2 mutation into corn lines is a time-consuming process. Since the fl2 mutant allele is semidominant, phenotyping based on kernel vitreousness is difficult and often ambiguous. Coleman et al. (1997). A rapid, gene-specific molecular assay is needed to detect the fl2 mutant allele and determine zygosity in candidate plants. This assay will greatly facilitate breeding efforts by reducing the time needed to select plants with desirable features.